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# Re: DB crasher

- Date: Mon, 22 Apr 1996 23:48:44 PDT
- From:
- Reply-to:
- cc: yduj@cs.stanford.edu, MOO-Cows.PARC@xerox.com

    --- Rich Connamacher wrote:
    >Tell the wizzes of that moo to upgrade to 1.7.9p2 or the latest 1.8.0,

    True, but there are quite a number of server hacks in there that prevent
    the transition being easy.  The server, I believe, is back in the 1.7.8
    stone age, but there is no way to tell as ;version() returns
    "2.2.3 (hacked)"!

    >because that already has a builtin task number monitor that's much more
    >effecient than such a clock and won't have the problem of erroniously
    >killing processes, because it simply won't let anyone begin any new
    >processes over their task quota limit.

    This is indeed better, I was simply mentioning an alternate way of dealing
    with the problem.

    >Although it's their moo so it's
    >their call, running a clock like that is an _extremely_ messy band-aid
    >fix to an old problem that doesn't exist anymore.  What's worse, the
    >chance that the moo will crash and loose data since the last checkpoint,
    >or the 100% certainty that all processes will suddenly crash and almost
    >certainly loose data in one way or another?  I'd opt to simply let it crash.

    Mosts tasks are trivial, any important tasks in progress will usually be
    written
    in such a way that eliminates the need for suspending.

    >(Note that, if there really were a true fork bomb attack on that moo,
    >unless the clock cycles so frequently as to lag the entire moo, the fork
    >bomb could grow so fast that the clock will choke and die trying to
    >keep up..  If they don't believe me, tell them to give me a prog bit on
    >their moo and an okay to go ahead and crash it.  Whoever wrote it
    >must not understand exponential mathematics.)

    I've only managed to slip one accidental fork bomb by it, and that was due
    to several objects running verbs forked at 2 second intervals.  (d'oh!)

    As for the clock dying trying to keep up, unless someone added pre-emptive
    multi-tasking when I wasn't looking, the server can kill ~15,000 tasks per
    suspend(0).  This ought to be enough to keep up with most fork bombs.

    As for a prog bit, it is hard enough to get a prog bit there when you AREN'T
    tring to crash the MOO . . .

    I think the guy understood exponential math just fine, as your garden variety
    fork bomb is stopped instantly.

    -manta

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